The present invention relates to various types of electronic musical instruments such as an electronic organ and an electronic piano, particularly, to a technique for enriching expressions of electronic musical instruments and, more particularly, to a technique for faithfully reflecting the will of a performer of the electronic musical instrument on a musical tone generated by the electronic musical instrument.
As a conventional method of adding a musical expression to a musical tone generated by an electronic keyboard musical instrument, initial touch control for detecting a key depression speed to control a musical tone, after touch control for detecting a pressure further acting on the depressed key to control a musical tone, and the like are performed.
In addition, a lateral movement of a keyboard as a whole is detected to provide a touch vibrato.
As described in U.S. Pat. No. 4,079,651, an L-shaped conductive elastic member is used and deformed upon key depression, a plurality of stationary contacts respectively connected to resistors are sequentially short-circuited to shift a contact position with a band-like resistor, thereby detecting a change in resistance and hence performing touch control.
As shown in Japanese Utility Model Laid-Open Nos. 63-195389 and 63-195380, a depression force upon key depression or the like is detected by a pressure-sensitive sensor to perform musical tone control is also proposed.
In addition, as shown in Japanese Patent Laid-Open No. 53-31001, a keyboard portion can be slightly moved laterally as a whole, a slit board having two through holes for symmetrically changing amounts of light transmitted through the through holes in correspondence with lateral movements is arranged, and optical signals obtained through the through holes are operatively detected and are used to control a musical tone.
Furthermore, as described in U.S. Pat. No. 4,314,227, there is provided an electronic musical instrument having nonstroke keys operable upon selective touching of patterns representing shapes of a large number of keys, wherein an output from a pressure-sensitive sensor is changed in accordance with a touch position and a touch force, thereby controlling a musical tone.
Japanese Patent Publication No. 53-5545 discloses a key depression speed detector of an electronic musical instrument to assign a touch response effect, wherein a switch is operated in synchronism with key depression, the number of clock pulses from a timing when its movable contact is connected to a normally closed stationary contact to a timing when the movable contact is connected to a normally open stationary contact is counted, a count output is obtained in correspondence with the key depression speed, and parameters such as the amplitude, frequency, tone color, and phase upon switching are determined in accordance with the count output.
This is a touch sensitive apparatus of the electronic musical instrument wherein the switch is utilized as a contact time difference switch.
A keyboard apparatus for an electronic keyboard musical instrument includes a plurality of keys pivotally supported on at least a key support member, and key switches which are turned on upon operations of the corresponding keys to control generation of musical tone signals.
In recent years, the following structure is very popular, as described in Japanese Utility Model Laid-Open No. 64-55990. Movable portions of key switches corresponding to the respective keys are protruded in a doom-like shape from the common base (for all keys) made of an elastic material such as synthetic rubber. The doom-like projection is deformed upon depression of a key, so that a movable contact in this projection is brought into contact with the paired fixed projection on a printed circuit board, thereby obtaining an electrical connection.
In addition, as described in Japanese Utility Model Laid-Open No. 61-198997, two key switches having the above arrangement are arranged at two different longitudinal positions for each key, and a difference between the ON time of one key switch and the ON time of the other key switch upon depression of the corresponding key is detected to perform touch response control.
Moreover, a presensor such as a stroke sensor for outputting a signal corresponding to a key depression stroke is arranged to attempt control of a musical tone in accordance with information prior to the normal key ON operation.
These conventional electronic musical instruments and input apparatuses for controlling their musical tones can only perform musical tone control common to all the keys. Even if a key depression speed and a key depression force can be detected in units of keys, only one type of signal is detected for each key. Therefore, only simple musical tone control can be provided to result in poor musical expressions.
In the conventional touch sensitive apparatus for the electronic musical instrument, a musical tone is controlled in accordance with only a time, i.e., a time interval value, required for switching the switch (contact time difference switch). This control is nothing to do with control of different switching states (i.e., the speed of the movable contact separated from the normally closed contact or the speed of the movable contact brought into contact with the normally open contact) caused by ways of key depression. Therefore, delicate musical tone expressions are impossible.
For example, in an actual musical performance by an electronic keyboard musical instrument performer, finger movements prior to the key ON operation or after the key OFF operation naturally express an attack (rise of a musical tone) or a release (a lingering tone). If these finger movements are reflected on the music, a more expressive music can be produced.
In a conventional electronic keyboard musical instrument, although key depression and key release (key ON and OFF), an initial strength upon key depression, an after touch during key depression, and the like can be detected and reflected on musical tones, contact states between the fingers and the key board in a state immediately prior to the key ON operation and a state immediately after the key OFF operation cannot be detected.
In a piano (acoustic piano), a tone color upon striking of a key is not determined by only a key depression strength and a key depression speed, but is delicately changed in accordance with the way of striking a key and the way of releasing a finger from the depressed key.
For example, a performance by striking a key from a state in which a finger is kept placed on this key (i.e., the key depression speed is abruptly increased from the initial speed=0) and a performance by striking a key by downward movement of a finger onto the key (the key depression speed is increased at almost the constant speed from the start to key depression) produce different tone colors although the key depression strengths are equal to each other.
An action in which the finger is slowly released from the depressed key and an action in which the finger is quickly released from the depressed key provide different lingering tone colors due to the following reason.
For example, when a key is gradually released, a damper is brought into contact with vibrating strings, and the tone color is gradually changed. When the finger is perfectly released from the key, vibrations of the strings are stopped, and the tone is perfectly stopped.
Therefore, different lingering tone colors are obtained until the tones are stopped in accordance with different finger release methods.
In the electronic keyboard musical instrument using the conventional electronic touch sensitive apparatus, the tone color and the volume level are solely determined in accordance with the final key depression speed regardless of different key depression methods. Control is nothing to do with actual key movements. At the time of a key release, a simple tone decay occurs in accordance with the time when the key is released. The tones are decayed independently of key release speeds and key movements (i.e., the finger is abruptly released from the key, the finger is released as if the finger plunks the key, or the finger is gradually released from the key).
It is, therefore, impossible to obtain a performance and expressions as in an acoustic piano.
In the conventional electronic musical instrument described above, only generation of musical tones can be controlled by key switches, and an expressive musical performance cannot be made. In an arrangement having two keys switches as touch response switches for each key, although a musical tone can be changed in accordance with a key depression speed, a satisfactory emotional expression cannot be obtained.
By arranging a presensor such as a stroke sensor, its information is combined with key depression speed information from the touch response switch to make an expressive performance which reflects the will of the performer.
Since the conventional all-sensing stroke sensors have complicated structures and are arranged independently of the key switches, the keyboard structure is complicated, and its assembly is complicated accordingly.